/*
Copyright (C) 1999 CERN - European Organization for Nuclear Research.
Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose 
is hereby granted without fee, provided that the above copyright notice appear in all copies and 
that both that copyright notice and this permission notice appear in supporting documentation. 
CERN makes no representations about the suitability of this software for any purpose. 
It is provided "as is" without expressed or implied warranty.
 */
package cern.jet.random.tdouble.engine;

/**
 * (Seemingly gigantic) table of good seeds for pseudo-random number generators.
 * <p>
 * <b>Implementation:</b>
 * <dt>This is a port of <tt>SeedTable.h</tt> used in <A
 * HREF="http://wwwinfo.cern.ch/asd/lhc++/clhep">CLHEP 1.4.0</A> (C++). CLHEP's
 * implementation, in turn, is part of <A
 * HREF="http://wwwinfo.cern.ch/asd/geant/geant4.html">GEANT 4</A>, a C++
 * simulation toolkit for High Energy Physics. Geant4, in turn, took the table
 * from the original FORTRAN77 implementation of the HEP CERN Library routine
 * RECUSQ. Each sequence has a period of 10**9 numbers.
 * 
 * @author wolfgang.hoschek@cern.ch
 * @version 1.0, 09/24/99
 */
public class RandomSeedTable {
    /**
     * The number of columns of the matrix (currently COLUMNS = 2).
     */
    public static final int COLUMNS = 2;

    // a m*n matrix, just stored as one-dim array
    // 215 * 2 entries
    private static final int[] seeds = new int[] { 9876, 54321, 1299961164, 253987020, 669708517, 2079157264,
            190904760, 417696270, 1289741558, 1376336092, 1803730167, 324952955, 489854550, 582847132, 1348037628,
            1661577989, 350557787, 1155446919, 591502945, 634133404, 1901084678, 862916278, 1988640932, 1785523494,
            1873836227, 508007031, 1146416592, 967585720, 1837193353, 1522927634, 38219936, 921609208, 349152748,
            112892610, 744459040, 1735807920, 1983990104, 728277902, 309164507, 2126677523, 362993787, 1897782044,
            556776976, 462072869, 1584900822, 2019394912, 1249892722, 791083656, 1686600998, 1983731097, 1127381380,
            198976625, 1999420861, 1810452455, 1972906041, 664182577, 84636481, 1291886301, 1186362995, 954388413,
            2141621785, 61738584, 1969581251, 1557880415, 1150606439, 136325185, 95187861, 1592224108, 940517655,
            1629971798, 215350428, 922659102, 786161212, 1121345074, 1450830056, 1922787776, 1696578057, 2025150487,
            1803414346, 1851324780, 1017898585, 1452594263, 1184497978, 82122239, 633338765, 1829684974, 430889421,
            230039326, 492544653, 76320266, 389386975, 1314148944, 1720322786, 709120323, 1868768216, 1992898523,
            443210610, 811117710, 1191938868, 1548484733, 616890172, 159787986, 935835339, 1231440405, 1058009367,
            1527613300, 1463148129, 1970575097, 1795336935, 434768675, 274019517, 605098487, 483689317, 217146977,
            2070804364, 340596558, 930226308, 1602100969, 989324440, 801809442, 410606853, 1893139948, 1583588576,
            1219225407, 2102034391, 1394921405, 2005037790, 2031006861, 1244218766, 923231061, 49312790, 775496649,
            721012176, 321339902, 1719909107, 1865748178, 1156177430, 1257110891, 307561322, 1918244397, 906041433,
            360476981, 1591375755, 268492659, 461522398, 227343256, 2145930725, 2020665454, 1938419274, 1331283701,
            174405412, 524140103, 494343653, 18063908, 1025534808, 181709577, 2048959776, 1913665637, 950636517,
            794796256, 1828843197, 1335757744, 211109723, 983900607, 825474095, 1046009991, 374915657, 381856628,
            1241296328, 698149463, 1260624655, 1024538273, 900676210, 1628865823, 697951025, 500570753, 1007920268,
            1708398558, 264596520, 624727803, 1977924811, 674673241, 1440257718, 271184151, 1928778847, 993535203,
            1307807366, 1801502463, 1498732610, 300876954, 1617712402, 1574250679, 1261800762, 1556667280, 949929273,
            560721070, 1766170474, 1953522912, 1849939248, 19435166, 887262858, 1219627824, 483086133, 603728993,
            1330541052, 1582596025, 1850591475, 723593133, 1431775678, 1558439000, 922493739, 1356554404, 1058517206,
            948567762, 709067283, 1350890215, 1044787723, 2144304941, 999707003, 513837520, 2140038663, 1850568788,
            1803100150, 127574047, 867445693, 1149173981, 408583729, 914837991, 1166715497, 602315845, 430738528,
            1743308384, 1388022681, 1760110496, 1664028066, 654300326, 1767741172, 1338181197, 1625723550, 1742482745,
            464486085, 1507852127, 754082421, 1187454014, 1315342834, 425995190, 960416608, 2004255418, 1262630671,
            671761697, 59809238, 103525918, 1205644919, 2107823293, 1615183160, 1152411412, 1024474681, 2118672937,
            1703877649, 1235091369, 1821417852, 1098463802, 1738806466, 1529062843, 620780646, 1654833544, 1070174101,
            795158254, 658537995, 1693620426, 2055317555, 508053916, 1647371686, 1282395762, 29067379, 409683067,
            1763495989, 1917939635, 1602690753, 810926582, 885787576, 513818500, 1853512561, 1195205756, 1798585498,
            1970460256, 1819261032, 1306536501, 1133245275, 37901, 689459799, 1334389069, 1730609912, 1854586207,
            1556832175, 1228729041, 251375753, 683687209, 2083946182, 1763106152, 2142981854, 1365385561, 763711891,
            1735754548, 1581256466, 173689858, 2121337132, 1247108250, 1004003636, 891894307, 569816524, 358675254,
            626626425, 116062841, 632086003, 861268491, 1008211580, 779404957, 1134217766, 1766838261, 1423829292,
            1706666192, 942037869, 1549358884, 1959429535, 480779114, 778311037, 1940360875, 1531372185, 2009078158,
            241935492, 1050047003, 272453504, 1870883868, 390441332, 1057903098, 1230238834, 1548117688, 1242956379,
            1217296445, 515648357, 1675011378, 364477932, 355212934, 2096008713, 1570161804, 1409752526, 214033983,
            1288158292, 1760636178, 407562666, 1265144848, 1071056491, 1582316946, 1014143949, 911406955, 203080461,
            809380052, 125647866, 1705464126, 2015685843, 599230667, 1425476020, 668203729, 1673735652, 567931803,
            1714199325, 181737617, 1389137652, 678147926, 288547803, 435433694, 200159281, 654399753, 1580828223,
            1298308945, 1832286107, 169991953, 182557704, 1046541065, 1688025575, 1248944426, 1508287706, 1220577001,
            36721212, 1377275347, 1968679856, 1675229747, 279109231, 1835333261, 1358617667, 1416978076, 740626186,
            2103913602, 1882655908, 251341858, 648016670, 1459615287, 780255321, 154906988, 857296483, 203375965,
            1631676846, 681204578, 1906971307, 1623728832, 1541899600, 1168449797, 1267051693, 1020078717, 1998673940,
            1298394942, 1914117058, 1381290704, 426068513, 1381618498, 139365577, 1598767734, 2129910384, 952266588,
            661788054, 19661356, 1104640222, 240506063, 356133630, 1676634527, 242242374, 1863206182, 957935844,
            1490681416 };

    /**
     * Makes this class non instantiable, but still let's others inherit from
     * it.
     */
    protected RandomSeedTable() {
        throw new RuntimeException("Non instantiable");
    }

    /**
     * Returns a deterministic seed from a (seemingly gigantic) matrix of
     * predefined seeds.
     * 
     * @param row
     *            should (but need not) be in [0,Integer.MAX_VALUE].
     * @param column
     *            shoould (but need not) be in [0,SeedTable.COLUMNS-1].
     * @return the seed at the indicated matrix position.
     */
    public static int getSeedAtRowColumn(int row, int column) {
        // the table is limited; let's snap the unbounded input parameters to
        // the table's actual size.
        int rows = rows();

        int theRow = Math.abs(row % rows);
        int theColumn = Math.abs(column % COLUMNS);

        int seed = seeds[theRow * COLUMNS + theColumn];

        // "randomize" the seed (in some ways comparable to hash functions)
        int cycle = Math.abs(row / rows);
        int mask = ((cycle & 0x000007ff) << 20); // cycle==0 --> mask = 0
        seed = seed ^ mask; // cycle==0 --> seed stays unaffected
        // now, each sequence has a period of 10**9 numbers.

        return seed;
    }

    /**
     * Not yet commented.
     * 
     * @return int
     */
    private static int rows() {
        return seeds.length / COLUMNS;
    }
}
